The present invention relates to a heat transfer system for a lamp assembly, such as an automotive headlamp, fog lamp, signal light, or taillight. More specifically, it relates to a lamp assembly having an external heat transfer plate, with or without a bulb shield, for transferring heat out of away from the lamp assembly to the ambient environment.
During use, the bulb of a typical lamp reaches relatively high temperatures and generates excess heat. Such excess heat from the bulb can melt, deform, or otherwise cause damage to the lamp housing surrounding the bulb, especially when the lamp housing is made from an inexpensive plastic material. While any side of the lamp housing may have one or more areas susceptible to heat damage, the top side of the lamp housing above the bulb generally suffers the greatest damage due to the excess heat rising from the bulb.
One way to prevent heat damage to the lamp housing is to increase the distance from the bulb to the sides of the lamp housing. Similarly, another way is to increase the overall volume of the cavity defined by the lamp housing for the bulb. Alternatively, the power output (i.e., wattage) of the bulb may be reduced, or the lamp housing may be made of a more expensive material with a relatively high resistance to heat. The problem with each of these known solutions is that they require either an increase in size, a reduction in power output, and/or an increase in the cost of manufacturing the lamp. Since the size and power output of most lamps is restricted and dictated by manufacturing and regulatory specifications, along with the low cost objectives for manufacturing, these known solutions are undesirable for substantially reducing or preventing heat damage to lamp housings from their bulbs.
An alternative solution to the problem of heat damage to lamp housings caused by bulbs involves the use of heat shields or bulb shields. An example of a heat shield for an automotive back light assembly is disclosed in U.S. Pat. No. 5,510,968 to Pokriefka et al., and an example of an automotive bulb shield is disclosed in U.S. Pat. No. 3,896,302 to Whitney. The problem with the heat shields and bulb shields known in the prior art, however, is that they are positioned internally within the lamp housing. Accordingly, while the heat shields and bulb shields of the prior art absorb some of the excess heat generated by the bulb, they do not remove or dissipate the absorbed heat outside and away from the lamp housing. As a result, the heat released internally by these heat shields and bulb shields of the prior art may still cause damage to the lamp housing.
Accordingly, it would be desirable to have a heat transfer system for a lamp assembly that overcomes the problems associated with the prior art by having an externally mounted heat transfer plate for transferring and dissipating heat outside of and away from the lamp assembly to the ambient environment. Such a heat transfer system would substantially reduce or prevent heat damage to the lamp housing from the bulb, without requiring an increase in the size of the lamp housing, a decrease in the power output, or an increase in the manufacturing cost of the lamp assembly.
The present invention provides a lamp assembly comprising a lamp housing defining and internal cavity and having at least one side with an opening. The lamp assembly also comprises a heat transfer plate attached to the at least one side, positioned outside of the internal cavity, and at least partially aligned with the opening to transfer heat away from the lamp housing. In addition, the lamp assembly may also comprise a bulb shield having an arm connected to the heat transfer plate, and a shell connected to the arm opposite the heat transfer plate, with the shell being adapted to at least partially cover a bulb.
The present invention further provides a lamp assembly comprising a bulb having a filament portion and a socket opposite the filament portion, and a lamp housing having a top side with an exterior surface and an opening aligned with the filament portion of the bulb. The lamp assembly also comprises a heat transfer plate mounted over the opening on the exterior surface of the top side to transfer heat away from the lamp housing. The lamp assembly further comprises a sealing gasket positioned between the heat transfer plate and the top side of the lamp housing.